This invention relates generally to analytic devices for distillable materials. More particularly, this invention relates to on-line petroleum crude analyzers which provides relevant information useful in controlling process variables so as to optimize distillation efficiencies and other interconnected downstream processes in a refinery.
Methods for analyzing petroleum crude feed stocks which involve complex analytical procedures are well known in the petroleum industry. For example, gas-liquid chromatograms utilizing spectrophotometric techniques can achieve a significant compositional breakdown of a petroleum crude sample. Such complete description of the crude sample can then be used to precisely define and optimize process variables to maximize both yields and general operating efficiency of a refinery.
Another method for analyzing a petroleum crude involves classification and hydrocarbon type analysis. In this method, the crude is distilled at atmospheric pressure into fractions having a boiling point up to 275.degree. C. and then further distilling at 40 mm of Hg into fractions boiling above 275.degree. C. Subsequently, specific gravities of each fraction are determined and the crude classified accordingly.
Unfortunately with the wealth of information available from analyzing crudes, at least two problems have persisted. The first is the complexity of equipment necessary to obtain required information. The second is the inability to obtain rapidly enough the required information to take into account sudden and often unexpected changes in the crude or hydrocarbon feedstock so as to vary appropriately process control elements such as valves and heaters.